Murgatroyd, 30, posted an Instagram video of her workout, which included squats, sit-ups, hip raises and sled pushes, all with the added weight of Shai (and fiancé Maksim Chmerkovskiy for the sled pushes!).

“Mum getting after it in the gym with some special helpers — Shai, @maksimc, and the amazing @timhartwigtrain. Working hard for that wedding body! #workingmom #fitnessmom,” Murgatroyd captioned the video.

Murgatroyd — who just finished up the most recent season of DWTS with partner Nick Viall — wrote a blog for PEOPLE about struggling to lose the last bit of post-baby weight.

RELATED VIDEO: Dancing With The Stars‘ Peta Murgatroyd On Her Body After Baby: ‘I Need Another Month!’

“At the beginning of the season I thought I’d be back at my pre-baby weight after a month but now that milestone has come and went and I’m still not at my normal weight,” she wrote in April. I feel good, though — so much more energy that I had at the beginning of the season — so I’m hoping maybe I’ll be there in another month!”